Known is an injection molding apparatus in which components are molded by injecting resin into a cavity, which is a space formed between a stationary side die and a movable side die.
In the process of molding an optical element, a positional misalignment between the stationary side die and the movable side die leads directly to a shape error of a product. Here, taking the case of a lens as an example, the above-mentioned positional misalignment corresponds to a misalignment of axes in the case where there is a misalignment between the central axes of the optically functional surfaces of the lens molded with a stationary side die and a movable side die, or the optical axes of the lens are tilted (intersect each other).
In order to prevent or stabilize such an axial misalignment, there is proposed a configuration in which the contact faces between the stationary side die and the movable side die is made to have taper shapes, and when the dies are clamped, the dies are made to follow the abovementioned taper shapes, thereby controlling the axial misalignment (for example, patent documents 1 and 2).